Charges: Grandson was mastermind in deadly robbery

The ambush robbery and murder of a 79-year-old Willmar church volunteer was plotted by her 17-year-old grandson, according to charges, which also detail how she was slashed with a 20-inch knife and strangled by a 19-year-old man while a third teenager acted as a lookout.

The ambush robbery and murder of a 79-year-old Willmar church volunteer was plotted by her 17-year-old grandson, according to charges, which also detail how she was slashed with a 20-inch knife and strangled by a 19-year-old man while a third teenager acted as a lookout.